To skip the long history and associated griping, scroll down to the short questions at the bottom
Older spacepak R22 system replaced when heat pump died and change to R410 was recommended. Previous system was working GREAT so went with advice of HVAC company to replace entire system (same company that did original install approx 13 years ago). Old system was 5 ton, don't have any more details (sorry)
Spacepak ESP-4860D with 3/4 hp blower motor at 1725 rpm
Paired to Trane XR12 4twr2060a1000ab outside
28 outlets in house (5.6 per ton)
System is working poorly at best (I say not at all). Freezing over constantly and can't keep house cool even on moderate days (b/c always in defrost mode). After several summers of letting the installer try to tweak the system, I was told today that "there is no way this system will work with only 28 outlets and there is no way it could have ever worked from the first day it was installed."
I was informed that the fan motor is "shot" and as a result it is often starting in reverse direction (so short answer was to get it going in right direction and leave fan switch in 'on' mode). I was told this is the result of not enough outlets and therefore too much back-pressure so not enough air is getting into the house and, therefore, not enough air is being pulled out of the house and across the coil so it is freezing up. And the motor died trying to push air into the house.
I was told I would need a new motor at the very least ($$$ installed for same 3/4 hp motor) and I was told that would be a short term fix and what I really needed was a new spacepak (the current unit has HEAVY rust from the constant freezing) and a new condenser outside b/c the Trane has been overworked. Most importantly, I needed at least 7 additional outlets and 10 would be preferred ($$$$$$ quote for condenser, spacepak and install with additional outlets).
To say the least, I was a bit unhappy.
When I asked how the old system was able to work GREAT with 28 outlets I was told that the new systems are much more efficient and that means less powerful fan/fan motor and as a result the current fan motor can't force the same amount of air into the house. Makes perfect sense (the air is a LOT less noisey - but it was never bothersome before).
My question then (I know, finally): Why can't I just swap the motor on the blower wheel with a larger, more powerful motor? I understand that it must still fit on the motor mount correctly in order to line up the drive shaft with the wheel, but certainly a 1 h/p motor would still fit and maybe even more.
Moreover, why not go with a motor that has multiple speeds so a higher rpm could be used on really hot days when needed, and a lower rpm used when not needed (but still enough to force the air out of my limited 28 outlets)?
Needless to say, I'm looking for another HVAC contractor given that I was never told to increase outlets (still have original install paperwork) and was specifically told it wouldn't be needed and all that was "possibly" needed was an increase of the supply duct, which was listed as an option that we chose to be safe - and now I'm told it could never have worked from the begining.
But its the weekend and so while I'm waiting to find another contractor, I'm just wondering why I can't go with a more powerful motor. FWIW, I notice that on my original spacepak paperwork it shows only a 3/4 hp motor as an option, but the current paperwork online shows a 1 h/p option (sounds like its for me :-).
Also, when I asked about the option of going with a multi-speed motor, I was told there was no way to control it from the thermostat. However, I notice that there is a fan relay on the spacepak (not in use with the current motor) and I know there are plenty of thermostats with fan speed controls.
Enough homeowner whining, the short questions are:
(1) can I install a more powerful motor in my spacepak such that it can push more air through my existing 28 outlets?
(2) if so, can I use a multi-speed motor and control it from the indoor thermostat (with a new thermostat of course)?
Thanks for any advice, and enjoy the weekend!